A pressing need exists for a dosage form for the controlled administration of nilvadipine for treating cardiovascular symptoms. The dosage form comprising nilvadipine would be therapeutically indicated for treating cardiovascular symptoms including angina pectoris, hypertension, congestive heart failure, and it would possess vasodilation properties for decreasing systemic vascular resistance.
The beneficial drug nilvadipine, 5-isopropyl-3-methyl-2-cyano-6-methyl-4-[3-nitrophenyl]-1,4-dihydro-3,5-py ridine-dicarboxylate, is disclosed in a patient study reported in the Journal of Clinical Pharmacology, Vol. 27, pp 293-296, 1987. The drug was administered in the study as a bulk, non-rate, uncontrolled dose that was unprotected from the changing environment of the gastrointestinal tract. Nilvadipine was administered by the prior art as a single oral dose devoid of rate-controlled delivery because nilvadipine is practically insoluble in aqueous media, about 1-2 .mu.g/ml, and accordingly it does not lend itself for formulation into a dosage form that administers the drug at a controlled and known rate per unit time.
In light of the above presentation, it will be appreciated by those versed in the dispensing art to which this invention pertains, that a pressing need exists for a rate-controlled dosage form that can deliver the valuable drug nilvadipine to a patient in critical need of nilvadipine cardiovascular therapy. The pressing need exists also for an oral dosage form that can deliver nilvadipine at a controlled rate in a substantially constant dose per unit time over a prolonged period of time for its beneficial hemodynamic effects, and substantially independent of the variable environment of the gastrointestinal tract. It will be appreciated further by those versed in the dispensing art that such a novel and unique dosage form that can administer nilvadipine in a rate-controlled dose over time, and simultaneously provide cardiovascular therapy, would represent an advancement and a valuable contribution to the art.